Coherent Modulation Of Squeezing Spectra Via Electromagnetically Induced Transparent Medium

Since Harris observed the phenomenon of electromagnetically induced transparency (EIT) in1991, much attention has been paid to it due to its applications in quantum information, quantum computation, and storage of optical information. EIT is one of the interference phenomena in which thmulti-level atoms driven by a strong coherent field is transparent for a probe field. There are many phenomena associated with EIT, such as lasing without inversion (LWI), coherent population trapping (CPT), electromagnetically induced absorption, giant nonlinear optics and storage of optical information, and so on, which attracts great attention. Especially, the storage of quantum optical information based on the EIT technique plays an important role in quantum communication. As is well known, photon is an ideal carrirer of information due to its fast propagation and weak interaction with other matters. Manipulation of information will need to stop the light in terms of storage of information based on EIT technique. On the other hand, the squeezing property of the probe light is a pure quantum one, which is an important application in quantum communication such as quantum teleportation. These studies will be constructed on the basis of full quantum EIT, which can be excellently explained. In the present thesis, we shall investigate the storage of optical information by using DSP theory, and the storage and revival of squeezing properties of light in the atoms. At the same time, we discuss the coherent modulation of the squeezing spctra of the probe light. This thesis is organized as follows: In chapter1, the EIT phenomenon and its development have been reviewed. The various applications and present studies on the EIT are presented.In chapter2, the interaction between the fields and the atoms by using semi-classical and quantum theory has been introduced, respectively. We choose a three-level A atomic system as an example to show the absorption and dispersion of a probe field as well as its low group veloccity. Besides, the EIT phenomenon has been explained by using dark-state.In chapter3, the conception of dark-state polariton is introdued, by which the realization of storage of optical quantum information has been interpretated.In chapter4, the polariton picture in the interaction of three multi-mode quantized fields with a five-level M-typeatomic ensemble driven by three classical control fields is derived. The storage (or retrieval) of the quantum state of light in (or from) the atomic polarization state is investigated. Especially in the retrieve process, we can reselse two probe fields simutansously or have a time delay on demand. This has a potential application in quantum information processing.In chapter5, we have examined the coherent modulation of the absorption and squeezing properties in a six-level tripod-type atomic system driven by the coherent perturbation fields under the condition of resonance and non-resonance. There will arise multiple transparent windows and multi-squeezing dips, which is induced by the coherent perturbation fields. By adjusting these parameters we find that the strength of the perturbation fields determines the width of the resonance absorption peaks and the distance between the squeezing dips. Additionally, we consider the influence of the ground-states dephasing rates to the squeezing survival and transfer and find that the maximum squeezing at the transparent points is squeezed by dephasing rates. These researches will have a potential role in quantum information and quantum communication.